Folding blade for a clearing apparatus with a blade

ABSTRACT

A folding blade for a clearing apparatus with a clearing blade includes a folding bar, a lever mechanism for pivotally mounting the folding bar on a base part of the clearing blade, and a spring element for arrangement between the base part and the lever mechanism, for returning the folding bar to an initial position in which the folding bar forms an extension of a blade plate of the clearing blade. The lever mechanism is designed in such a way that the folding bar is pivotable from the initial position to a retracted position along a first pivoting path by overcoming a spring force of the spring element, and that the folding bar is pivotable from the retracted position to the initial position along a second pivoting path due to the spring force.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Swiss patent application CH555/2022, filed 10 May, 2022, the content of which is herein incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a folding blade for a clearing apparatus with a clearing blade, comprising a folding bar, a lever mechanism for pivotally mounting the folding bar on a base part of the clearing blade, and a spring element for arrangement between the base part and the lever mechanism, for returning the folding bar to an initial position in which the folding bar forms an extension of a blade plate of the clearing blade. The lever mechanism is designed in such a way that the folding bar is pivotable from the initial position to a retracted position along a first pivoting path by overcoming a spring force of the spring element, and the folding bar is pivotable from the retracted position to the initial position along a second pivoting path due to the spring force. The invention further relates to a clearing blade having such a folding blade.

Description of Related Art

Folding blades of this type are known. They are used in particular for clearing equipment of snow clearing machines. However, they are also used for clearing equipment of municipal vehicles, rail vehicles or tractors, whereby the clearing equipment can be designed as integrated components of the respective vehicles or as exchangeable attachments.

Originally, there are two types of rotating snow clearing machines, the snow blower and the snow tiller. The snow blower has a large paddle wheel, the axis of which is oriented in the direction of travel. The diameter of the paddle wheel determines the clearing width. The rotating blades of the paddle wheel carry away the snow at the front and transport it to the outside with the help of centrifugal force. There, the snow is then ejected through an opening. The snow tiller has rollers whose axes are oriented at a right angle to the direction of travel. The rollers have reels that are arranged in a spiral around the rollers and run inwards as a result of the rotary motion. The rotating reels now carry away the snow and transport it to the center of the machine. There it is in turn ejected through an opening.

The dual-stage snow blower combines these two systems in one machine. The cutting reels are mounted in front, and the blower wheel is located behind them. The cutting reels and blower wheel are optimally matched to each other by gears and ratios in order to be able to work efficiently. This system combines the advantages of the cutting reels, which can remove the snow better and allow a greater width with a lower overall height, with those of the blower wheel, which allows a further ejection with increased snow mass.

In order to cushion the impact when the clearing blade hits an obstacle on the ground and to make it easier to drive over the obstacle, the clearing blade is equipped with a folding blade. This is often referred to as a “collision safety device”. Folding blades have one or more folding bars that are pivotably mounted on a base part of the clearing blade. The folding blades are usually designed as wear parts, so-called clearing blades. Because they are in constant contact with the ground surface to be cleared during operation, they wear out and have to be replaced when a certain degree of wear is reached.

Such a folding blade is available, for example, on dual-stage snow blowers from the applicant Zaugg AG Eggiwil, Eggiwil, Switzerland, e.g. the model SF 7270 KS. The folding bar is split in the middle so that the two elements can trigger separately on the left or right, depending on the point of impact of the obstacle. Both elements are pivoted on a base part of the clearing blade via a horizontal hinge axis running transverse to the direction of travel. When they hit an obstacle, they are pressed backwards. The restoring force is provided by a hollow rubber spring, which is installed between the base part and the folding bar and is compressed when folded back. Other suppliers also offer snow removal vehicles with similarly designed collision guards, e.g. Westa GmbH, Weitnau, Germany for their 6570, 7370 and 750 snow blowers.

Folding blade systems are also known for snow plows. The folding blade forms the lowest section of the snow plow blade. Typically, part of the folding assembly deflects forward, i.e. in the direction of travel. This is not a problem in the case of a snow plow, but corresponding solutions cannot be transferred to snow blowers because the rotating cutting reels are located in front of the blade and the foldable element would collide with them.

Conventional folding blades improve the clearing result, operating safety and protect the cutter and the carrier vehicle when driving over obstacles. However, when the folding blade system is triggered, the snow blower can be pushed upwards, causing the cutter to “bounce”. This causes strong vibrations in the carrier vehicle and impairs the clearing result in the area of the obstacle. Furthermore, it can happen that the folding bar gets stuck in its retracted position after being released and does not return to its initial position. In such cases, the clearing operation must be interrupted. The clearing blade with the folding blade is then raised briefly with the aid of the corresponding lifting device of the carrier vehicle to allow the folding blade to return to its initial position.

DE 10 256 541 A1 (Fritz Sperber GmbH) proposes a mechanism to prevent the folding blade from bouncing. The corresponding folding bar is guided in such a way that it does not take up any additional space below the base part of the clearing blade when it is pivoted back. The mechanism creates a virtual pivot axis for the folding bar, which is located in front of the clearing blade. It includes a linkage with two arms or levers that are not parallel to each other and, if necessary, a cam track that serves as a guide during the pivoting movement and can be arranged in a rib or a stiffening plate. The mechanism is designed to swing back after hitting an obstacle and return to the initial position along the same predetermined pivoting path.

This mechanism improves the pivoting back of the folding bar after hitting an obstacle. However, problems can still arise, particularly when returning to the initial position, especially if the folding bar comes into contact with the material to be cleared again during return, which can lead to complete return being prevented for a longer period of time. This in turn leads to a deteriorated clearing result.

BRIEF SUMMARY OF THE INVENTION

It is the problem of the invention to create a folding blade belonging to the technical field initially mentioned, which enables an improved return of the folding bar and thus a better clearing result.

The solution to the problem is defined by the features of claim 1. According to the invention, the lever mechanism is designed in such a way that the second pivoting path is different from the first pivoting path.

This means that the lever mechanism offers at least two degrees of freedom in at least one or more partial sections of the path between the initial position and the retracted position. The partial sections can extend along the path or be very short in the manner of a switch or branch. In particular, due to the different triggering of the first pivoting path—by contact with an obstacle that must be overcome by the folding bar—and the second pivoting path—by the spring force of the spring element—, in practice there are also actually different movements when pivoting back on the one hand and when resetting on the other. As a result, during a complete cycle, each point of the folding bar moves from the initial position to the retracted position and back to the initial position along a closed curve that includes a non-zero area. In particular, in the vicinity of one or both end positions, the two pivoting paths may coincide, i.e., in such a section of the pivoting paths there is only one degree of freedom.

The initial position is characterized in that the folding bar forms an extension of the blade plate of the clearing blade. In particular, the front main surface of the folding bar in this position lies essentially in the same plane as the front surface of the blade plate along the contact line between the clearing blade and the folding bar. Generally, the folding bar in this position has a positive pivot angle, i.e., its lower free end is located forward in the direction of travel.

The retracted position can be defined by an end stop. In practice, however, the folding bar does not have to be pivoted back to this stop every time an obstacle is overcome. In the case of smaller obstacles, resetting can already take place before the end stop has been reached. Nevertheless, the lever mechanism should preferably be designed in such a way that different pivoting paths are also provided in this case. This is particularly the case if the first pivoting path and the second pivoting path differ from each other in an area in the neighborhood of the initial position. In particular, it is preferred that the first pivoting path and the second pivoting path also differ at least in a region in which the folding bar assumes a positive pivoting angle.

A single spring element or several spring elements arranged in series and/or parallel can be used in the folding blade according to the invention. The spring elements are preferably hollow rubber springs. These are insensitive to external influences such as dirt or ice formation, have a long service life and relatively low costs. However, other types of tension or compression springs, e.g. helical springs, torsion springs or gas springs, can also be used. In principle, suitably (actively or passively) controlled hydraulic or pneumatic cylinders can also be used as spring elements. The spring element or elements do not have to be mounted directly on the base part or on the lever mechanism. In particular, the spring element can also interact with the lever mechanism via transmission means, e.g. rods or cables.

The lever mechanism comprises pivoted levers. In addition, it can also include elements such as guides, stops or cable pulls to control or restrict the movement of the levers.

The base part of the clearing blade comprises the blade plate (the scraper plate) itself and any elements permanently connected to the clearing blade, such as stiffening plates or profiles, base frames, fastening profiles, etc. Accordingly, the lever mechanism may engage one or more of these elements.

The folding blade according to the invention can follow a different pivoting path when returning to the initial position than before when overcoming an obstacle. This means that the pivoting path can be optimally adapted to the requirements: When pivoting away from the initial position, the folding bar should move back so that the obstacle can be passed without vertical forces on the clearing blade and without lifting it, if possible. The return to the initial position should be as fast and unhindered as possible once the obstacle has been passed. The lever mechanism is therefore preferably designed in such a way that the folding blade first folds forwards (i.e. in the direction of travel, in particular until it assumes a positive pivoting angle) when returning from the retracted position before it is lowered to the initial position. Obstacles up to a certain maximum height can thus be overcome without the clearing blade bouncing and without interrupting the clearing operation, and it is ensured that the folding bar returns to its initial position as quickly as possible after overcoming the obstacle and independently during travel, without being prevented from this return by external influences, such as contact with the material being cleared.

Taking into account the above-mentioned requirements, the folding blade according to the invention can also be designed in such a way that all elements of the folding blade are arranged above a lower edge of the clearing blade and at the same time completely behind this clearing blade.

The lever mechanism and the spring element of the folding blade according to the invention can be designed to save space so that conflicts with other elements of the clearing apparatus, e.g. a blower wheel, a suspension of the clearing blade or the like, are reliably avoided. Likewise, a lever mechanism can be designed to minimize vibrations after hitting an obstacle.

Typically, in the initial position, the folding bar forms a first positive angle with a vertical line. This is in particular in the range 30-60°, especially 40-50°. In the retracted position, on the other hand, the folding bar assumes a negative angular position so that the obstacle can be passed.

Advantageously, therefore, the second pivoting path comprises a first path region, adjacent to the retracted position, in which the pivoting path corresponds to a pure pivoting movement about a single axis of rotation, and a second path region in which the pivoting path corresponds to a superimposition of two pivoting movements about two spaced axes of rotation. The second travel range can be directly adjacent to the first travel range and extend to the initial position, or there is a further travel range between the first travel range and the second travel range and/or the second travel range and the initial position.

With such a design of the lever mechanism, which allows such a second pivoting path, it can thus be achieved that the folding bar is only lowered again during the return to the initial position when its pivoting position has reached such a positive value, which allows further clearing of the ground and/or allows a deflection of the material to be cleared onto the clearing blade. This prevents the folding bar from coming into contact with the material to be cleared at an early stage during the return movement and thus pivoting back again immediately, which can ultimately prevent resetting for some time.

In preferred embodiments of the invention, the lever mechanism comprises an elbow lever, having a first elbow lever element pivotally connected to the base part of the clearing blade and having a second elbow lever element connected to the folding bar in a rotationally fixed manner, wherein the second elbow lever element and the first elbow lever element are hingedly connected to each other and wherein the spring element acts on the second elbow lever element.

Both the first elbow lever element and the second elbow lever element can be connected directly or indirectly to the base part or the folding bar. The spring element can act directly or indirectly on the second elbow lever element. In particular, the folding blade can comprise a number of elbow levers which are arranged parallel to one another and pivotably mount the folding bar on the base part at positions spaced apart in the transverse direction.

An elbow lever can be designed to be mechanically very robust, it is inexpensive and its function is little susceptible to external influences such as contamination or icing. The elbow lever requires comparatively little force deflection, so the mechanical loads are low. The deflection takes place smoothly during the pivoting of the folding bar mounted on the elbow lever, so that impact effects on the bearing or mounted elements are avoided.

Advantageously, the spring element acts on the second elbow lever element via a deflection mechanism. In particular, this means that the spring element can be arranged directly behind the clearing blade in a space-saving manner without having to select the direction of the force acting on the lever mechanism in an unfavorable manner.

Preferably, the deflection mechanism comprises a deflection lever rotatably mounted on the base part and a coupling rod, wherein the spring element and the coupling rod are mounted on the deflection lever at spaced pivot points and wherein the coupling rod is pivotally connected to the second elbow lever element. A deflection lever of this type enables the approximately vertical spring force of a spring element arranged in a space-saving manner behind the clearing blade to be deflected into a force acting virtually horizontally on the second elbow lever element. This enables reliable resetting of the folding bar without the risk of the elbow lever blocking after passing the obstacle due to an unfavorably acting spring force.

Instead of or in addition to a deflection lever, the deflection mechanism can also comprise a cable pull for deflecting the spring force. A combination of spaced compression and tension springs can also be used, for example. Blocking in the retracted position can also be prevented by suitable stops, e.g. at the middle joint of the elbow lever. Compared with these alternatives, however, the solution with a deflection lever is mechanically more resilient and less susceptible to contamination or icing.

Preferably, the deflection lever, the coupling rod and the spring element are designed in such a way that a restoring force on the folding bar in the retracted position is less than in the initial position. This prevents the folding bar from being pivoted back from the initial position due to the force exerted by the material to be cleared, while preventing unnecessary resistance when passing an obstacle, i.e. after the pivoting movement has been “triggered”.

A preferred embodiment of the invention comprises a first stop for the first elbow lever element arranged on the base part, wherein in the retracted position the first elbow lever element rests against the first stop. As long as this contact exists, the elbow lever has only one degree of freedom. If the contact is released, after a certain pivoting movement in the direction of the initial position, two degrees of freedom result.

Preferably, the folding blade comprises a second stop for the second elbow lever element arranged on the base part, the second stop being designed in such a way that in a section of the second pivoting path the second elbow lever element is guided by an outer contour of the second stop.

For this purpose, the second elbow lever element can in turn have a specifically shaped outer contour for interacting with the outer contour of the second stop, e.g. an outer contour which, depending on the rotational position of the second elbow lever element, causes an alternating distance between the second stop and the articulation of the spring element and/or the elbow lever joint, i.e. acts as an eccentric. The specifically shaped outer contour of the second elbow lever element is in particular convex in shape and is formed on the side of the second elbow lever element facing the second stop.

Particularly preferably, both the first stop and the second stop are present, and the first stop limits the second pivoting path in the first path section, adjacent to the retracted position, to a pure pivoting movement, while the second stop in the second path section, adjacent to the initial position, guides the elbow lever in such a way that two pivoting movements are superimposed. The superposition is in particular such that a lowering of the folding bar in the direction of the initial position results, in particular while largely maintaining the pivot angle of the folding bar. The pivoting angle according to the initial position is thus essentially already achieved before the return is completed. Preferably, at least one third of the lowering is carried out at least in a travel range adjacent to the initial position, while the pivot angle is changed by a maximum of 5° in this range.

The deflection mechanism and the two stops thus ensure overall that the folding bar swings back from the retracted position and first folds forward again (to a positive angular position) before it sinks again.

Advantageously, in the initial position, the second stop cooperates with the second elbow lever element to prevent movement of the folding bar along the first pivoting path upon a force acting on the folding bar from a rear side of a main plane of the folding bar. In particular, this prevents substantially vertical forces that cannot be caused by an obstacle in the direction of travel from triggering the pivoting movement.

In a clearing blade according to the invention, the folding blade is pivotably arranged on the clearing blade such that it is pivotable from an initial position, in which the folding bar of the folding blade forms an extension of a blade plate of the clearing blade, to a retracted position, wherein the folding bar does not enter a path space defined by the clearing blade with the folding blade either during pivoting from the initial position to the retracted position along the first pivoting path, or during pivoting from the retracted position to the initial position along the second pivoting path.

This travel space corresponds to a space below a plane defined by the lower edge of the folding bar in the initial position when the blade is mounted on the vehicle and ready for operation. This prevents the clearing blade from lifting due to vertical forces acting on the folding bar from the ground or obstacle.

In a dual-stage snow blower, the blade preferably has a central receiving opening for a blower wheel, and a first folding blade is arranged on a first side of the receiving opening and a second folding blade is arranged on a second side of the receiving opening. In this case, the folding bars of the first folding blade and the second folding blade extend into an area below the receiving opening. The distance between the folding bars in the transverse direction is advantageously so small that material to be cleared cannot pass between the folding bars in substantial quantities when they are in their initial position. In particular, the distance is 5 cm or less.

Further advantageous embodiments and combinations of features of the invention result from the following detailed description and the totality of the patent claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Further advantages features and details of the various embodiments of this disclosure will become apparent from the ensuing description of a preferred exemplary embodiment or embodiments and further with the aid of the drawings. The features and combinations of features recited below in the description, as well as the features and feature combination shown after that in the drawing description or in the drawings alone, may be used not only in the particular combination recited but also in other combinations on their own without departing from the scope of the disclosure.

The following is an advantageous embodiment of the invention with reference to the accompanying figures, wherein:

FIG. 1 depicts an oblique view of an embodiment of the folding blade according to the invention;

FIG. 2 depicts an exploded view of the lever mechanism of the folding blade;

FIG. 3A and 3B depict a side view of the folding blade in the initial position and in the retracted position;

FIGS. 4A-E depict the motion sequence of the folding blade when it pivots back after hitting an obstacle; and

FIGS. 5A-E depict the motion sequence of the folding blade during return to the initial position.

In principle, the same parts are given the same reference signs in the figures.

DETAILED DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

As used throughout the present disclosure, unless specifically stated otherwise, the term “or” encompasses all possible combinations, except where infeasible. For example, the expression “A or B” shall mean A alone, B alone, or A and B together. If it is stated that a component includes “A, B, or C”, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C. Expressions such as “at least one of” do not necessarily modify an entirety of the following list and do not necessarily modify each member of the list, such that “at least one of “A, B, and C” should be understood as including not only one of A, only one of B, only one of C, or any combination of A, B, and C.

FIG. 1 shows an oblique view of an example of the folding blade according to the invention, viewed laterally from the rear. The example relates to a clearing apparatus with a clearing blade width of 220 cm, but the folding blade shown can also be used for larger and smaller clearing blade widths. The folding blade 1 is arranged on the clearing blade 2 and comprises two folding bars 6 made of steel. Visible in FIG. 1 is the right half of the clearing blade up to a central blower wheel housing 3. The left side is essentially symmetrical to the right side and comprises its own folding bar 6, whereby in the initial position shown, the two folding bars 6 meet in the center up to a distance of approx. 5-10 mm.

The folding blade 1 comprises a base part 5, the folding bar 6 and a lever mechanism 10, via which the folding bar 6 is connected to the base part 5 or the clearing blade 2, respectively. For this purpose, two bearing plates 7, 8 in particular are welded to the clearing blade 2. Further bearing points are formed on the base part 5. The lever mechanism 10, which is described in more detail below in connection with FIG. 2 , is acted upon by a hollow rubber spring 30 acting as a compression spring and being pivotably mounted on the clearing blade 2 via a spring guide rod 31. The spring guide rod 31 presses on a contact roller 41, which is mounted at one end of a deflection lever 40. The deflection lever 40 is pivotably mounted on the clearing blade 2 between the bearing plates 7, 8 and comprises two parallel, essentially triangular lever plates 40 a, 40 b, which are connected to one another in the region of the three corners via axles; the contact roller 41 is mounted on one of these axles. At the end opposite the contact roller 41, the deflection lever 40 is pivotably connected to a coupling rod 45 via an axle 42. This is designed as a steel profile with two bearing tubes welded to each end and acts on the lever mechanism 10, as described in detail below.

The lever mechanism 10 is described in more detail with reference to the exploded view in FIG. 2 . It consists largely of steel components. It comprises two lever elements 11, each comprising two lateral lever arms 11 a, 11 b which are connected to each other by a connecting plate 11 c. The connecting plates 11 c are screwed by means of several screws to one each of two fastening plates 6 a welded to the folding bar 6 The folding bars 6 can thus be easily replaced as soon as they are worn out.

An axle 12 is mounted at the free ends of the lever arms 11 a, 11 b of each lever element 11. Via this, a rotary arm 13 is pivotably mounted at its first end on the lever element 11. The rotary arm 13 comprises a bearing tube 13 a and two lever arms 13 b, 13 c arranged non-rotatably on the bearing tube 13 a. The bearing tube 13 a accommodates the axle 12. The lever element 11 and the rotary arm 13 thus form an elbow lever, and the axle 12 forms the axis of rotation of the elbow lever. At the second end of the rotary arm 13, an axle 14 is mounted on the lever arms 13 b, 13 c. Via this, the rotary arm 13 is pivotably mounted on the base part 5 of the folding blade 1 (see FIG. 3A, 3B).

A further axle 46 is mounted between the two lever elements 11, on which the coupling rod 45 is pivotably mounted. The various axles are each accommodated in plain bearings formed by bearing bushes made of a polyoxymethylene copolymer (POM-C).

FIGS. 3A, 3B show a side view of the folding blade in the initial position and in the retracted position, respectively. The direction of travel points to the right. In the initial position shown in FIG. 3A, both the front main surface of the base part 5 and the front main surface of the folding bar 6 lie in the extension of the clearing blade 2. They enclose an angle of 45° with the vertical. In the context of the present documents, this angle is defined as “positive”.

In the initial position, the hollow rubber spring 30 is in the maximum relaxed position. It pushes the deflection lever 40 obliquely downward, counterclockwise to its end position, which is defined by the stop 55 that interacts with the lever plates of the deflection lever 40. The stop 55 is adjustable by means of a set screw, so that the end position of the lever mechanism 10 and thus the end position of the folding bar 6 in the initial position can be adjusted. The coupling rod 45 acts on the lever element 11, which is firmly connected to the folding bar 6 (cf. also FIG. 5E, where the corresponding linkage can be seen), and pushes it together with the folding bar 6 in the direction of travel. In the initial position, the lever element 11 is oriented practically horizontally, while the second element of the elbow lever, the pivoting arm 13 mounted on the base part 5, forms an angle of slightly more than 90° with the lever element 11 and points practically vertically upwards.

In the retracted position shown in FIG. 3B, the front main surface of the folding bar 6 encloses an angle of −70° with the vertical. It is thus pivoted by 115° with respect to the initial position. Accordingly, the hollow rubber spring 30 is in a compressed position and the deflection lever 40 is pivoted clockwise with respect to the initial position. The axis 12, which forms the axis of rotation of the elbow lever, has moved upwards between the initial position and the retracted position together with the folding bar 6 and it is in contact with the stop 51. The angle between the elements of the elbow lever, i.e. the lever element 11 and the rotating arm 13, is again approximately 90°.

FIGS. 4A-4E illustrate the movement sequence of the folding blade when it pivots back after hitting an obstacle. The folding blade 1 typically contacts the obstacle 9 with the lower end of the folding bar 6 (FIG. 4A). As long as the obstacle 9 does not exceed a certain height, 30 mm in the example shown, it can be driven over without raising the clearing blade: The folding bar 6 folds back, and the obstacle 9 passes under the base part 5 of the folding blade 1, which is firmly connected to the clearing blade 2. The folding back is triggered by the action of the obstacle 9, which initially causes the folding bar 6 to pivot in a clockwise direction (FIG. 4B). This also causes the lever element 11, which is fixed to the folding bar 6, to rotate clockwise around the axis 12. Due to the elbow lever, the rotating arm 13 thereby moves clockwise around the axis 14, which is fixed to the base part 5, so that the axis of rotation of the elbow lever, the axis 12, and thus the folding bar 6 are moved upwards. This superimposed movement takes place until the rotating arm 13 stops against the corresponding stop 51 (FIG. 4C). Subsequently, a pure rotary movement takes place around the axis 12 of the elbow lever until a sufficient negative pivot angle is reached that the obstacle 9 can be passed (FIGS. 4D, 4E).

During pivoting-back, the lever element 11 acts on the hollow rubber spring 30 via the coupling rod 45 and the deflection lever 40, compressing the spring.

FIGS. 5A-5E show the movement sequence of the folding blade when it is returned to the initial position. The return movement takes place due to the spring force of the compressed hollow rubber spring 30. It starts as soon as the force of the obstacle is removed. The hollow rubber spring 30 acts on the deflection lever 40 via the spring guide rod 31 and moves it counterclockwise. This results in a substantially linear compressive force of the coupling rod 45 on the lever element 11, which is fixedly connected to the folding bar 6 (FIG. 5A). Due to

the fact that the rotating arm 13 rests against the stop 51, this initially results in a purely rotational movement about the axis 12, so that the folding bar is pivoted in a counterclockwise direction in the direction of the initial position. As soon as the lever element 11 contacts the stop 53 arranged on the base part 5 of the folding blade 1 (FIG. 5B), the elbow lever is also pivoted about the axis 14 via which the rotary arm 13 is mounted on the base part 5. This results in a superposition of the two pivoting movements, controlled by the downward sliding of the lever element 11 along the stop 53 (FIG. 5C).

In contrast to the pivoting back as described in connection with FIG. 4 , an intermediate position is now reached (FIG. 5D), in which the folding bar 6 has already largely assumed its original pivoting position, but is still in a raised position, above the ground. Finally, the folding bar 6, further guided by the interaction between the lever element 11 and the stop 53, is moved downward in a practically linear movement until it reaches the initial position (FIG. 5E).

The invention is not limited to the illustrated embodiment. In particular, the folding blade can have further movable and/or immovable elements. The geometry of the levers, the bearings and the spring element may be chosen differently. As described above, in particular the lever elements interacting with stops can have a specific outer contour in order to control or influence this interaction.

In summary, the invention creates a folding blade that provides improved folding bar return and thus better clearing results. 

What is claimed is:
 1. A folding blade for a clearing apparatus having a clearing blade, the folding blade comprising: a) a folding bar; b) a lever mechanism configured to pivotally mount the folding bar on a base part of the clearing blade; c) a spring element arranged between the base part and the lever mechanism, the spring element configured to return the folding bar to an initial position in which the folding bar forms an extension of a blade plate of the clearing blade; and wherein the lever mechanism is configured such that the folding bar is pivotable from the initial position to a retracted position along a first pivoting path by overcoming a spring force of the spring element, and such that the folding bar is configured to pivot from the retracted position to the initial position along a second pivoting path due to the spring force; and wherein the lever mechanism is configured such that the second pivoting path is different from the first pivoting path.
 2. The folding blade according to claim 1, wherein the second pivoting path comprises: a first path section, adjacent the retracted position, in which the pivoting path corresponds to a pure pivotal movement about a single axis of rotation, and a second path section in which the pivoting path corresponds to a superposition of two pivotal movements about two spaced axes of rotation.
 3. The folding blade according to claim 1, wherein: the lever mechanism comprises an elbow lever comprising a first elbow lever element hingedly connected to the base part of the clearing blade and comprising a second elbow lever element connected to the folding bar in a rotationally fixed manner, the second elbow lever element and the first elbow lever element are hingedly connected to one another, and the spring element is configured to act on the second elbow lever element.
 4. The folding blade according to claim 3, wherein the spring element is configured to act on the second elbow lever element via a deflection mechanism.
 5. The folding blade according to claim 4, wherein: the deflection mechanism comprises a deflection lever rotatably mounted on the base part and a coupling rod, the spring element and the coupling rod are mounted on the deflection lever at spaced pivot points, and the coupling rod is pivotally connected to the second elbow lever element.
 6. The folding blade according to claim 5, wherein the deflection lever, the coupling rod and the spring element are configured and arranged such that a restoring force on the folding bar in the retracted position is less than in the restoring force in the initial position.
 7. The folding blade according to claim 3, comprising a first stop for the first elbow lever element arranged on the base part, wherein in the retracted position the first elbow lever element rests against the first stop.
 8. The folding blade according to claim 2, wherein the second elbow lever element comprises a second stop arranged on the base part, the second stop configured such that in a section of the second pivoting path the second elbow lever element is guided by an outer contour of the second stop.
 9. The folding blade according to claim 8, wherein, in the initial position, the second stop is configured and arranged to cooperate with the second elbow lever element to prevent movement of the folding bar along the first pivoting path upon a force acting on the folding bar from a rear side of a main plane of the folding bar.
 10. The folding blade according to claim 3, comprising a second stop for the second elbow lever element arranged on the base part, the second stop configured such that in a section of the second pivoting path the second elbow lever element is guided by an outer contour of the second stop.
 11. The folding blade according to claim 10, wherein, in the initial position, the second stop is configured and arranged to cooperate with the second elbow lever element to prevent movement of the folding bar along the first pivoting path upon a force acting on the folding bar from a rear side of a main plane of the folding bar.
 12. A clearing blade, comprising: a folding blade comprising a) a folding bar; b) a lever mechanism configured to pivotally mount the folding bar on a base part of the clearing blade; c) a spring element arranged between the base part and the lever mechanism, the spring element configured to return the folding bar to an initial position in which the folding bar forms an extension of a blade plate of the clearing blade; and wherein the lever mechanism is configured such that the folding bar is pivotable from the initial position to a retracted position along a first pivoting path by overcoming a spring force of the spring element, and such that the folding bar is configured to pivot from the retracted position to the initial position along a second pivoting path due to the spring force; and wherein the lever mechanism is configured such that the second pivoting path is different from the first pivoting path; and wherein the folding blade is pivotally arranged on the clearing blade so as to pivot from an initial position, in which the folding bar of the folding blade forms an extension of a blade plate of the clearing blade, to a retracted position, wherein the folding bar does not enter a path space defined by the clearing blade with the folding blade either during pivoting from the initial position to the retracted position along the first pivoting path or during pivoting from the retracted position to the initial position along the second pivoting path.
 13. The clearing blade according to claim 12, further comprising: a central receiving opening configured to receive at least one of a blower wheel and a snow blower wheel, a first folding blade arranged on a first side of the receiving opening, a second folding blade arranged on a second side of the receiving opening, and wherein the folding bars of the first folding blade and the second folding blade are arranged to extend into an area below the receiving opening. 